One piece hydraulic disc brake caliper with one way plumbing

ABSTRACT

A hydraulic disc brake caliper that includes a housing that has first and second side portions and first and second end portions that cooperate to define a braking opening. The housing also includes first and second piston receiving openings and first and second fluid openings. The caliper also includes a bolt received in the second fluid opening that includes a shaft having a portion of a fluid path defined in the outer surface thereof that includes at least one channel and at least one reduced diameter portion. The fluid path extends from the first fluid opening to the second fluid opening. The at least one channel and the at least one reduced diameter portion are part of the fluid path and are in fluid communication between the first and second piston receiving openings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/498,133, filed Jul. 6, 2009, the entirety of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to hydraulic disc brakes, and moreparticularly, to a hydraulic disc brake caliper with one way plumbing.

BACKGROUND OF THE INVENTION

In recent years, certain high performance bicycles have includedhydraulic disc brakes. Hydraulic disc brake systems typically include acaliper housing, a first movable brake pad and a second fixed or movablebrake pad. The movable brake pad is typically attached to a piston thatis movable in response to fluid pressure applied via a hydraulic fluidconduit in the caliper housing. The brake pads are positioned on eitherside of a rotor, which is attached to the front or back wheel of abicycle. Upon the application of fluid pressure to the piston orpistons, the brake pads come into contact with the rotor, therebyapplying frictional resistance and causing the bicycle to slow down orstop.

Hydraulic disc brake systems for bicycles are typically actuated by abrake lever attached to a bicycle handlebar. They also typically includea master piston in a master cylinder which is actuated by the brakelever. The master cylinder contains a hydraulic fluid and is in fluidcommunication with the disc brake caliper via a fluid conduit. The brakepads are typically spaced apart from the rotor by a predetermined gap.As the lever is contracted towards the handlebar, the master pistonmoves, thereby forcing liquid out of the master cylinder and into aconduit connected to the caliper housing. The movement of fluid ecaliper housing causes the pistons to move, eventually bringing thebrake pads into contact with the rotor.

When initially filling the hydraulic disc brake system (including themaster cylinder and the caliper), the system must be bled to remove gasbubbles from the system and optimize performance of the brakes. Manyprior art calipers include a branched hydraulic fluid pathway therein.In other words, after the fluid enters through the fluid inlet, itbranches into two separate conduits, one that goes to one piston andanother that goes to the piston on the other side (and another branch tothe fluid outlet). This can make bleeding the brakes difficult becausethe bubbles get caught in the various branches. A need exists for ahydraulic disc brake caliper that is easy to bleed.

SUMMARY OF THE PREFERRED EMBODIMENTS

In accordance with one aspect of the present invention, there isprovided a hydraulic disc brake caliper that includes a housing that hasfirst and second side portions and first and second end portions thatcooperate to define a braking opening, first and second piston receivingopenings and first and second fluid openings. The housing also includesa bolt received in the second fluid opening that includes a shaft havinga portion of a fluid path defined in the outer surface thereof thatincludes at least one channel and at least one reduced diameter portion.The fluid path extends from the first fluid opening to the second fluidopening. The at least one channel and the at least one reduced diameterportion are part of the fluid path and are in fluid communicationbetween the first and second piston receiving openings.

In accordance with another aspect of the present invention, there isprovided hydraulic disc brake caliper that includes a housing havingfirst and second side portions and first and second end portions thatcooperate to define a braking opening. The housing also includes firstand second fluid openings defined therein and a fluid path. A bolt isreceived in the second fluid opening in the housing. The bolt includes ashaft having a portion of a fluid path defined in the outer surfacethereof that includes at least one channel and at least one reduceddiameter portion. The at least one channel and the at least one reduceddiameter portion are in fluid communication. The fluid path extends fromthe first fluid opening through the portion of the fluid path defined inthe outer surface of the bolt, and to the second fluid opening. In apreferred embodiment, the portion of the fluid path defined in the outersurface of the bolt includes first and second reduced diameter portionsthat are separated by a blocking portion and the fluid path extends fromthe first fluid opening, through the at least one channel, through thefirst reduced diameter portion, through the second reduced diameterportion and to the second fluid opening.

In accordance with another aspect of the present invention, there isprovided a bolt for use with a hydraulic disc brake caliper. The boltincludes a head and a shaft extending outwardly from the head. The shaftincludes a threaded portion having a diameter, at least one channeldefined in the outer surface of the threaded portion, first and secondreduced diameter portions defined at least partially circumferentiallyaround the shaft, and a blocking portion separating the first and secondreduced diameter portions.

The present invention is applicable to all types of devices and is notlimited to bicycles.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more readily understood by referring to theaccompanying drawings in which:

FIG. 1 is a side elevational view of a bicycle with a front disc brakeassembly and a rear disc brake assembly in accordance with an embodimentof the present invention;

FIG. 2 is a side elevational view of the front disc brake assemblycoupled to a front fork and a front disc brake operating mechanism ofthe bicycle illustrated in FIG. 1;

FIG. 3 is a side elevational view of the rear disc brake assemblycoupled to a rear fork and a rear disc brake operating mechanism of thebicycle illustrated in FIG. 1;

FIG. 4 is a perspective view of a bolt for use with a one piecehydraulic disc brake caliper in accordance with an embodiment of thepresent invention;

FIG. 5 is a perspective view of a one piece disc brake caliper with thebolt of FIG. 4 and showing the conduits and ports it hidden lines;

FIG. 6 is a cross-sectional top plan view of the disc brake caliper ofFIG. 5 taken along line 6-6 of FIG. 5;

FIG. 7 is a cross-sectional top plan view of the disc brake caliper ofFIG. 5 taken along line 7-7 of FIG. 5, which includes the pistons andbrake pads; and

FIG. 8 is a schematic showing the fluid path in the conduits and bolt ofthe disc brake caliper of FIG. 5.

Like numerals refer to like parts throughout the several views of thedrawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1-8, a preferred embodiment of a bicycledisc brake caliper 11 is described. Bicycle disc brake caliper 11 ispreferably a hydraulic brake disc caliper operatively connected to ahydraulic brake lever assembly.

It will be appreciated that terms such as “front,” “back,” “top,”“bottom,” “side,” and the like used herein are merely for ease ofdescription and refer to the orientation of the components as shown inthe figures. It should be understood that any orientation of the caliper11 and the components thereof described herein is within the scope ofthe present invention.

As shown in FIG. 1, a bicycle 10 with a front disc brake assembly 12 anda rear disc brake assembly 14 is illustrated in accordance with apreferred embodiment of the present invention. Other than the calipers,the front and rear disc brake assemblies 12 and 14 are relativelyconventional fluid operated disc brakes fixedly coupled to a frame 13.Therefore, many of the components of the disc brake assemblies 12 and 14will not be discussed or illustrated in detail herein except as modifiedby the preferred embodiments of the present invention, as discussedbelow. Furthermore, it will be understood that the bicycle disc brakecaliper 11 can be used with either the front disc brake assembly 12 anda rear disc brake assembly 14.

Specifically, front disc brake assembly 12 is fixedly coupled to a frontfork 15 of frame 13, and rear disc brake assembly 14 is fixedly coupledto rear fork 17 of frame 13. Frame 13 includes a handle bar 19 mountedto front fork 15 to steer the bicycle 10. Bicycle 10 includes a pair ofwheels 16 rotatably coupled to the bicycle frame 13. One wheel 16 iscoupled to front fork 15, and one wheel 16 is coupled to rear fork 17.Each wheel 16 has a disc brake rotor 18 fixedly coupled thereto in aconventional manner.

The bicycle 10 and various components thereof are relativelyconventional. Therefore, bicycle 10 and its various components will notbe discussed or illustrated in detail herein, except as these componentsrelate to bicycle disc brake caliper 11 and front and rear disc brakeassemblies 12 and 14 in accordance with the preferred embodiments of thepresent invention, Moreover, front and rear disc brake assemblies 12 and14 are substantially identical. Therefore, it will be understood thatcaliper 11 can be used with both front disc brake assembly 12 or reardisc brake assembly 14. It will further be understood that the front andrear disc brake assemblies 12 and 14 can include calipers 11 that haveany number of pistons therein. For example, the calipers 11 shown inFIGS. 2 and 3 are four piston type calipers. However, the calipers 11shown in FIGS. 5-8 include only two pistons. Accordingly, a caliper withany number of pistons is within the scope of the present inventionprovided the calipers 11 include one-way plumbing, as described below.

Front disc brake assembly 12 basically includes caliper 11 and a brakeoperating mechanism or lever assembly 28 a. Caliper 11 includes acaliper housing 20, a pair of friction members 22, and a plurality ofpistons 24 disposed in the housing 20 (as shown in FIG. 7). Caliperhousing 20 is fixedly coupled to front forks 15 in a conventional mannerusing threaded fasteners. First and second friction members 22 arecoupled to caliper housing 20 to form a rotor receiving slottherebetween. At least one of the friction members 22 is movablerelative to caliper housing 20, and preferably both friction members aremovable relative to caliper housing 20. At least one piston 24 ismovably coupled to caliper housing 20. Preferably, each piston 24 ismovably coupled to caliper housing 20.

Referring to FIGS. 5-8, caliper housing 20 is preferably formed of rigidmetallic material such as cast aluminum. In a preferred embodiment,caliper housing 20 is formed as a single unit or piece. In other words,it is not formed as two halves that are bolted together, as is common inprior art calipers. However, in an alternative embodiment, the caliperhousing 20 can comprise two separate halves that are fixedly coupledtogether by a plurality of bolts. Caliper housing 20 includes a firstfluid opening or fluid inlet 32 for receiving a fluid, typicallyhydraulic oil. Caliper housing 20 also includes a second fluid openingor fluid outlet 34 for receiving a bolt 50. The first and second fluidopenings 32 and 34 can be threaded, but do not have to be.

Caliper housing 20 preferably includes at least two ports or pistonreceiving openings 36 a and 36 b for receiving a piston 24, as shown inFIGS. 5-8. The piston receiving openings 36 a and 36 b are arranged tooppose one another. As shown in FIG. 7, each piston 24 is arranged tomove one of the friction members 22 toward disc brake rotor 18 (thebraking direction).

Each piston receiving opening 36 is preferably an annular opening sizedand configured to receive one of the pistons 24 therein. Moreover, eachpiston receiving opening 36 also preferably includes a circumferentialgroove 41 for receiving a sealing member 38 for preventing fluid fromescaping therefrom.

The seals are annular members formed of a resilient material such asrubber or flexible plastic. Each seal acts to circumferentially seal theinternal area of one of the piston receiving openings 36 from theoutside of caliper housing 20 when pistons 24 are arranged in pistonreceiving openings 36. Therefore, when actuating fluid is supplied topiston receiving openings 36, pistons 24 are moved toward rotor 18.Accordingly, friction members 22 are also moved toward disc brake rotor18 to produce a stopping action on rotor 18, and therefore, wheel 16.

Preferably, caliper housing 20 has two friction members movably coupledthereto, as discussed above. Moreover, friction members are preferablymovably coupled to caliper housing 20 such that a rotor receiving slotis formed therebetween. Each friction member basically includes a platewith a friction material fixedly coupled thereto in a conventionalmanner. Each plate is preferably formed of a rigid metallic material ina conventional manner. Each plate includes a mounting hole for slidablyreceiving a mounting pin therethrough. Mounting pin is partiallythreaded at one end and receives a securing member on the opposite endto secure friction members to caliper housing in a conventional manner.Drawings showing these components are shown in U.S. Pat. No. 6,491,144,the entirety of which is incorporated herein by reference.

Generally, as is best shown in FIG. 6, the caliper housing 20 iscomprised of four sections or portions, first and second side portions26 a and 26 b and first and second end portions 27 a and 27 b, thatcooperate to define a braking opening 25.

Piston receiving openings 36 a and 36 b are in fluid communication withfirst and second fluid openings 32 and 34 via a network of fluidconduits 37 and the fluid path defined through bolt 50 (discussedbelow). Thus, when actuating/hydraulic fluid is supplied to caliperhousing 20, the actuating fluid flows through the network of conduits 37a, 37 b, 37 c and 37 d, through the fluid path in bolt 50 and into thepiston receiving openings 36. For ease of description and because theconduits 37 a, 37 b, 37 c and 37 d operate in generally the same manner,the conduits may be referred to herein generically without the “a,” “b,”etc. suffix (same with the piston receiving openings 36 a and 36 b). Forexample, the conduits may be referred to individually as first conduit37 a, second conduit 37 b, third conduit 37 c or fourth conduit 37 d orthey may be referred to generically as conduit(s) 37.

As shown in FIG. 6, first conduit 37 a extends from first fluid opening32, passes through the piston receiving opening 36 a and into second endportion 27 b. In a preferred embodiment, second conduit 37 b extendsthrough second end portion 27 b in a direction that is generallyparallel to the direction that the pistons move (the braking direction).Third conduit 37 c extends from second conduit 37 b and to pistonreceiving opening 36 b. Fourth conduit 37 d extends from pistonreceiving opening 36 b back to second conduit 37 b and to second opening34. As can be seen in FIGS. 5 and 6, bolt 50 is adapted to direct fluidfrom second conduit 37 b to piston receiving opening 36 b via third andfourth fluid conduits 37 c and 37 d.

With reference to FIG. 4, bolt 50 includes head 52, a shaft 54, firstand second reduced diameter portions 56 a and 56 b, a plurality ofchannels 58 and a blocking portion 59 separating the first and secondreduced diameter portions 56 a and 56 b. In a preferred embodiment, theshaft 54 of the bolt 50 includes three axially extending channels 58arranged circumferentially therearound and spaced apart 120°, as isshown in FIG. 4. However, any number of channels 58 (e.g., one or more)are within the scope of the present invention. Also, the channels 58 donot have to be spaced equidistant from one another. The channels 58preferably extend parallel to the axis of the shaft 54. However, this isnot a limitation on the present invention. For example, the channelscould extend in a spiral around the shaft 54. The goal of the channels58 is to allow fluid to flow from the end of the shaft 54 furthest fromthe head 52 to the first recessed portion or reduced diameter portion 56a no that it can be directed to the third fluid conduit 37 c. If thechannels 58 were to extend in a spiral shape, it will be understood thatthe fluid is still flowing generally axially along the outside of theshaft 54, but that it is not necessarily parallel to the axis.Therefore, as used herein, generally axially means the distance traveledby the channels can be parallel to the axis or non-parallel to the axisas long as the total distance is further in an axial direction than in atransverse direction.

As is best shown in FIG. 6, the shaft 54 of bolt 50 is received in anopening 45 in a fluid coupling unit 40 and is threaded (via threads 60)into second fluid conduit 37 b. It will be understood that the fluidcoupling unit 40 is a generic fluid coupling unit and any such unit iswithin the scope of the present invention. As shown in FIG. 8, the fluidpath extends from first fluid opening 32, through first fluid conduit 37a and piston receiving opening 36 a through second fluid conduit 37 b,through the channels 58, through the first reduced diameter portion 56a, through third fluid conduit 37 c, to piston receiving opening 36 b,through fourth fluid conduit 37 d, through the second reduced diameterportion 56 b and out through the fluid coupling unit 40 to the mastercylinder (via the hydraulic line 86). This is the path that fluid takeswhen filling the caliper 11. In other words, all of the fluid conduits37, reduced diameter portions 56, piston receiving openings 36, channels58 and the fluid coupling unit 40 are all in fluid communication along anon-branched continuous fluid path. In a preferred embodiment, as isshown in FIG. 6, a portion of the second recessed portion 56 b islocated in the housing 20 and a portion of the second recessed portion56 b is located in the fluid coupling unit 40. The assembly can includeo-rings (not shown) between the fluid coupling unit 40 and housing 20and/or bolt head 52 for sealing the fluid path.

The interior surface 46 of the opening 45 in the fluid coupling unit 40has a diameter and has a hole 47 defined therein that is in fluidcommunication with the hydraulic line 86 extending from the fluidcoupling unit 40. As can be seen in FIG. 6, the diameter of the secondreduced diameter portion 56 b has a diameter that is less than thediameter of the inner surface 46 of the fluid coupling unit 40 and thediameter of the first reduced diameter portion 56 a has a diameter thatis less than the diameter of the inner surface of fluid conduit 37 b.This creates a space that is part of the fluid path.

As is shown in FIG. 4, the first and second reduced diameter portions 56a and 56 b extend circumferentially around the shaft 54. In a preferredembodiment, the first and second reduced diameter portions 56 a and 56 bextend all the way or 360° around the shaft 54. However, this is not alimitation on the present invention. In another embodiment, the firstand second reduced diameter portions 56 a and 56 b may only extendpartially around the shaft 54. It will be understood that an inventiveaspect of the present invention is that at least a portion of the fluidpath extends axially along the shaft 54 and is open to the outside ofbolt 50.

This arrangement of the conduits 37 and fluid path through the bolt 50makes the entire brake system (from caliper to lever assembly) easier tobleed than the prior art. As described above, many prior art systemshave branched conduit networks. In other words, the fluid enters throughan inlet and then branches to the pistons on either side of the rotor.In the present invention, the fluid path provides for one-way,continuous fluid flow with no branches. As shown by the solid arrows inFIG. 8, this provides a one-way path when filling the caliper housing 20with fluid. And, as shown by the dashed arrows in FIG. 8, this providesa one-way path for bleeding air/gas, which allows the air/gas to be moreeasily removed from the fluid in the braking system. For example, thebrake system bleeding technique taught in the SAINT Braking SystemTechnical Service Instructions (SI-8CZ0E), published by Shimano Inc. inMay, 2005, the entirety of which is incorporated herein by reference,can be used to bleed the brakes. It will be understood that, as usedherein, one-way does not mean that the fluid can only move in onedirection, but it means that the plumbing or conduit system is notbranched. Fluid going into the piston receiving openings 36 is notconsidered a branch.

Referring again to FIGS. 1-3, brake operating mechanisms 28 a and 28 bare conventional disc brake operating mechanisms. Therefore, brakeoperating mechanisms 28 a and 28 b will not be discussed or illustratedin detail herein. It will be understood that the calipers shown in FIGS.1-3 are for illustrative purposes only. Brake operating mechanisms 28 aand 28 b are provided to control disc brake assemblies 12 and 14. Brakeoperating mechanisms 28 a and 28 b are preferably fixedly mounted onhandle bar 19 adjacent the hand portions of handle bar 19. Accordingly,brake operating mechanisms 28 a and 28 b are operated in a conventionalmanner such that disc brake assemblies 12 and 14 move friction membersfrom a release position in which bicycle wheels 16 and the disc brakerotors 18 are free to rotate, and a braking position. In the brakingposition, disc brake assemblies 12 and 11 apply a braking force againstdisc brake rotor 18 to stop rotation of bicycle wheels 16 and disc brakerotors 18.

Brake operating mechanisms 28 a and 28 b will now be described in moredetail. Basically, brake operating mechanisms 28 a and 28 b are designedto actuate the disc brake assemblies 12 and 14 in a conventional mannerto apply a forcible gripping action on disc brake rotor 18 to stoprotation of one of the front wheels 16. Brake operating mechanism 28 bactuates rear disc brake assembly 14 and brake operating mechanism 28 aactuates front disc brake assembly 12. Brake operating mechanism 28 b isidentical to brake operating mechanism 28 a except brake operatingmechanism 28 b is a mirror image of brake operating mechanism 28 a. Eachof the brake operating mechanisms 28 a and 28 b basically includes abrake lever 80, a hydraulic or master cylinder 81, hydraulic or masterpiston 82, and an actuation fluid reservoir 83. Preferably, each of thebrake operating mechanisms 28 a and 28 b is a single unit, which ismounted on handlebar 19.

In particular, referring to either one of the brake operating mechanisms28 a and 28 b, brake lever 80 includes a mounting portion 84 and a leverportion 85. Mounting portion 84 is designed to be clamped onto handlebar 19 in a conventional manner. Mounting portion 84 is integrallyformed with master cylinder 81 such that master cylinder 81, masterpiston 82 and actuation fluid reservoir 83 are all supported on mountingportion 84 of brake lever 80. Lever portion 85 is pivotally coupled tomounting portion 84 for movement between a release position and abraking position. Normally, lever portion 84 is maintained in a releaseposition in a conventional manner.

Master piston 82 is movably mounted within master cylinder 81 in aconventional manner. More specifically, actuation fluid reservoir 83 ismounted on master cylinder 81 and is in fluid communication with theinterior bore of master cylinder 81 for supplying actuation fluidthereto. Master piston 82 is connected at one end to lever portion 85for axially moving master piston 82 within master cylinder 81.Accordingly, actuation of lever portion 85 causes master piston 82 tomove axially within master cylinder 81. This movement of master piston82 within master cylinder 81 directs fluid pressure through a hydraulicline 86 which is coupled to one of the disc brake assemblies 12 and 14via fluid coupling units 33. Thus, the pressurized actuating fluidcauses the pistons 24 and friction members to move so as to engage discbrake rotors 18 to stop rotation of wheels 16.

It will be understood that due to the reversibility of the fluid pathdescribed above, regardless of which reduced diameter portion, sideportion, end portion, conduit, port, piston receiving opening, etc. isdesignated as “first” or “second” in the specification, that whenreading the claims below, either of the reduced diameter portions, sideportions, end portions, conduits, ports, piston receiving openings, etc.can be considered “first” or “second.” The specific one designated as“first” or “second” in the drawings is not a limitation on the presentinvention.

The embodiments described above are exemplary embodiments of a thepresent invention. Those skilled in the art may now make numerous usesof, and departures from, the above-described embodiments withoutdeparting from the inventive concepts disclosed herein. Accordingly, thepresent invention is to be defined solely by the scope of the followingclaims.

1-13. (canceled)
 14. A bolt for use with a hydraulic disc brake caliper,the bolt comprising: a head, and a shaft extending outwardly from thehead, wherein the shaft includes a threaded portion having a diameter,at least one channel defined in the outer surface of the threadedportion, first and second reduced diameter portions defined at leastpartially circumferentially around the shaft, and a blocking portionseparating the first and second reduced diameter portions.
 15. The boltof claim 14 wherein the at least one channel extends parallel to theaxis of the shaft.
 16. The bolt of claim 15 wherein the shaft includesmore than one channel defined therein that extend parallel to the axisof the shaft.
 17. The bolt of claim 16 wherein the first and secondreduced diameter portions extend circumferentially around the shaft andhave a diameter that is less than the threaded portion and the blockingportion.
 18. The bolt of claim 17 wherein the first and second reduceddiameter portions and the blocking portion are positioned between thethreaded portion and the head.
 19. The bolt of claim 17 wherein theshaft includes three channels that extend parallel to the axis of theshaft and are spaced about 120° apart from one another.